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Your brain is designed to filter out sounds that your ears hear to concentrate on a particular sound. This evolved as a natural safety tool. For a million years in nature, our ancestors depended on their brains to filter out non-threatening sounds to be able to concentrate on threatening ones. Or to listen for prey to hunt.

Think of yourself talking to someone at a noisy party. Your brain filters out all the other conversations so you can listen to the person talking to you.

In a similar way, you filter out a lot of information that's in a room when you play, say, a guitar amp. You filter out most room reflections, hums and buzzes, structure-borne vibrations such as light bulbs vibrating and making ringing sounds, etc. A mic can't do this.

2. You don't listen to your guitar amp with your ear an inch from the speaker.

Though you can filter out a lot of the sounds around you to concentrate on the tone of your amp, you do hear them, and they do affect your perception.

3. Don't expect to truly capture the sound of "live."

Your ears are omnidirectional. Even the best multichannel recording techniques do not convincingly capture real sound. You know you're not listening to a live band, for example, even when listening to 5.1 mixes. Or 8.1 mixes. It's not the same.

With that, let's explore a few types of mics and their strengths and limitations:

Dynamics:

Your ordinary Shure SM57-style dynamic mic is actually a very fine recording mic, and an excellent transducer. Its strengths are that it's extremely robust and is able to capture the sound of a guitar speaker up close, and it can also do a nice job at a reasonable distance. The weakness of dynamic mics are that the method of transducing sound waves requires that the physical movement of a relatively heavy diaphragm. So it's more difficult to reproduce transients, and the attack portion of the waveform is a little more rolled off. It's also more accurate at the midrange than the low end or high end. People say mics like the 57 are midrange-heavy. Actually, they're high end and low end deficient with a relatively slow transient response. They are not horribly sensitive to proximity effect.

They're absolutely great for capturing certain elements of a guitar amp tone, and depending what you want to do with them, dynamic mics are well worth using. The key to getting a more natural sound with them is to use them close-in in combination with other mics.

Ribbons:

Ribbons are little corrugated pieces of aluminum suspended between two magnets. They are inherently fragile; a puff of wind can blow out the ribbon. But their lightness makes their transient response very fast. They have a very natural sound. The drawback is that even the most robust and best ones are very, very sensitive to proximity effect; close-in they exaggerate bass, and they therefore sound pretty dark. They also don't exhibit a lot of high end detail. Most roll off around 10KHz. EQ is needed to balance out their sound. The good news is that they have extremely low distortion and self-noise, and you can goose the high end with EQ to balance their sound out without increasing harshness. They're also figure 8 pattern mics, so even close in, they will pick up some room sound.

Blended with, say, a dynamic to capture the sound of the room, they can bring a nice naturalness to your recording. Alone, with EQ, they can sound very natural and real as well. The drawbacks are their fragility, their need for EQ, and the good ones are priced like a good condenser mic. The cheap ones aren't very good, but that's also the case with cheap condensers.

Condensers:

Condenser mics have a capsule that consists of a polarized backplate made of metal, with a charged diaphragm made of a very light material, such as mylar. This allows for fast transient response, and great sensitivity to detail. Because of their need for electrical polarization, they have to be phantom powered, or powered by a power supply (in the case of tube mics), and they also have to have a built in preamp to amplify the tiny signal they generate to even microphone level.

They go into distortion if too close to a guitar amp, and sound horrible when that happens. Or they blow up. So they need to be placed a bit farther back than a dynamic or even some ribbons, such as the Royer models.

While condensers' frequency response is theoretically more accurate than dynamics or ribbons, many are voiced to sound good with vocals, so they have a "presence bump" that brings a gentle rise in frequency response starting around 1-2 KHz and sometimes extending the rest of the way until they roll off around 15-18KHz.

The active electronics and nature of a condenser makes them a little more like a microscope, and there are distortion artifacts that can make recordings made with them a little harsh if the EQ is pushed beyond a certain point.

There are probably thousands of methods that can be used in combination to capture the sound of a guitar amp, but keep in mind that none is perfect. I like to use a dynamic up close, blended with a ribbon about 3-6 feet back, and higher up to approximate what my ears are hearing. I don't worry about stereo so much, simply because I still have to fit the amp sound into a mix with other instruments.

On a clean amp, I might add a condenser like the Blue Dragonfly, to give the blend a little more presence. But as you add mics, you have to be very careful not to cause phase cancellation issues, and a phase switch can help determine if you are screwing this up or not.

Some folks advocate miking the back of an open cab in addition to the front. I think this isn't a good idea; just use a room mic, and you'll pick up plenty of wall reflection from the back of the cab. I don't know anyone who listens to their guitar amp standing both in front and back of it at the same time.

Where do you put the mics? You MUST experiment. Every amp, every room, every mic is different. Have a friend play and move the mics around with headphones on until you're satisfied. An inch can make a difference! If you're alone, it's just going to take longer, but if you are after that elusive natural sound, you can record different placements, and listen back, until you're happy.

There is no substitute for experimentation, and no book can give you more than a starting point! Finally, take notes when you've found a good spot. Take a picture of the setup. Use a tape measure to keep track of distances and mic heights. Do what you have to do to document everything so that you can do it again.

But also remember, it's going to change when you use a different amp, or move anything so much as an inch. And that includes the amp being in a different room, or a different part of the room. It's going to sound a little different. Get used to not having a "formula." That's the art of it!

When I got my Kemper Profiling Amp I was struck by how the stock profiles done with a Blue Cactus (condenser) sounded better than the rest. I just gravitate toward those profiles. Not only do they sound better, they have a distinctive sound. Like a favorite cab, speaker, pickup, amps, fretboard material, etc... I may not know exactly what makes it good, I just know I like what I am hearing. After reading your post, I think what I am hearing is the added presence with that mic?

Oddly enough, when I was at NAMM this year the best info and education I got was from my visit to the Blue, Royer, Audix and Kemper booths.
I had to go to Blue to let them know how great their mic sounded with the Kemper. The response was- thank you...what is a Kemper? The rep gave me a similar education as you have Les, on the differences between a dynamic, condenser and ribbon. I have heard so many great thing about the Royer mics I just figured the Blue Cactus was the same thing...nope, totally different animals Royer is a ribbon, Cactus is a condenser.

I went to the Kemper booth and asked about the Cactus profiles. I met the guy from Nashville that created many of the profiles from Kemper. He said he was blown away by the performance of the Cactus and agreed that they were some of the best profiles. Amp wise he was struck by a Silvertone that he profiled with the Cactus. 'Silverclone' is the name of the profile...

While I was intrigued with why the mic made such a difference with recording and profiling, I am most interested in making my live sound as good as it can be. Going in I was thinking I just need to spend the money and Royer is going to get me to the next level. Or maybe get a Cactus for live performance, it worked for the Kemper why not for live? Now that I have a better understanding of the different types of mics and their application, Strengths and weaknesses, I think my tried and true Audix i5 will continue to be my go to mic for live close mic'ing. Audix has a new condenser that looks pretty good for live applications (CX 212B) maybe I'll give that a whirl...

In any event, the mic and its application can make a huge impact on the sound. I wish I had the patience and the opportunity to mess around with this in a live setting. Reality is, I just need to set it an forget it. I am not playing big enough stages to set up multiple mics on a cab only to have a numb nut sound guy not help me get the most out of it.

I don't think it's worth spending $3000 on a relatively delicate tube mic like the Cactus for live playing. Even a Royer at $1300 is pretty likely to be damaged playing live. But they're great for recording.

F'rinstance a puff of wind can damage the Royer - this can happen with someone opening the door, or accidentally holding it near a kick drum or bass amp while someone suddenly decides it's time to warm up. Rock stars use them live, but they can afford to re-ribbon them if there's a problem.

One of the things I like about the Cactus is that for a condenser it's very natural sounding. By the way, for a third the price, so is the Dragonfly. And for a tenth of the price, if you like the condenser sound, the Bluebird is a nice little mic!

This is a very helpful discussion.
Any suggestions specific to an acoustic guitar?

Yup. And a lot of them depend on what you're going for. Here are a few things to think about, the first of which is:

Will this be a solo acoustic guitar recording, or does the guitar need to blend into a mix with other instruments? And if it needs to blend, will that be with other acoustic instruments or a mix of acoustic and electric instruments? I use very different techniques for each.

For a solo acoustic guitar, I like a very natural sound. So after the instrument itself, the most important thing is the room, because you probably want to record in stereo, or the image in the speakers is just going to be a giant five foot guitar in mono (depending on how far apart the speakers are). A very simple way to get a great stereo recording of acoustic guitar is to use a coincident pair, using small diaphragm condensers, like this (only, you know, actually connect the mics with some cables!):

You can also do this with dynamic mics, ribbons, and large diaphragm condensers, but for acoustic guitar I prefer SDCs. Small Diaphragm Condensers (SDCs) have a faster transient response, and are actually more accurate than large diaphragm condensers like you see on vocals, etc. Their increased accuracy comes from the fact that LDCs have more inherent resonances. It's simply physics, and LDC designers use these resonances to enhance certain ranges that the mic picks up.

Whole symphony orchestras were often recorded with just a pair of SDCs hung over and in front of the orchestra proscenium (though the trend has been to add some spot mics in certain sections), so they don't need to be close to the instrument. You have to experiment a little to find the right balance of instrument-to-room sound. Start a few feet back and go from there. Get closer to the mics to pick up less room, and further back if you want to hear more room.

I like to close-mic the instrument with a high quality ribbon mic *if it's needed*, but this is not necessary unless the room isn't good sounding. The ribbon sounds natural enough that it doesn't sound too "fizzy", whereas spot miking an acoustic with a condenser can make the recording sound a little too "electric" to my ear.

In fact, a good ribbon sounds wonderful with an acoustic guitar, but it will probably need a little top end EQ. You do get a beautiful, natural sound with a good one. Some of the cheaper ones really suck, though, so if I only bought one mic for acoustic guitar, it'd be something like a Neumann KM series mic, that is sort of a studio standard and much less than a good ribbon mic. On a budget the Oktava SDCs are killer - in fact, even if you're not on a budget. They're very, very good if you get one of the real Russian ones (there are Chinese fakes that do not sound as good on the market!). In fact, I prefer the Oktavas to the Neumanns for overheads, but that's another story.

For an acoustic guitar track that has to blend with a band, there are a few things to play around with. If you want to capture the rhythm and drive of a strummed acoustic, and get a little grit, too, here's what to do:

Believe it or not, a 57 captures an acoustic guitar well for this exercise. What I do is compress the recorded track, and run an aux send to a dirt box! The aux return fader can then be blended in to give the acoustic guitar a little bit of grunt. This can be very cool, if used sparingly. Very sparingly, ok?

If I want a shimmery acoustic guitar track to blend in on top, just to add sparkle, I use an SDC close, mic the 12th fret pointed toward the soundhole about 6"-10" away, and EQ out the bottom, so what you hear is the pick on the strings and the shimmer. This can be really nice - think some of the blends in the old CSN&Y mixes.

For a bluegrass mix, I'd probably use the coincident pair, but a little closer-in, and definitely use the ribbon as a spot mic.

There are a TON of other techniques that people use; there are engineers that put a mic over the player's shoulder, and all kinds of other contraptions, so try anything that comes to mind!

It's important to keep in mind that with an acoustic instrument, there is a distance from the mic where it's like a lens coming into focus. Listen carefully as you move the mic around and you can hear it. This distance will vary from mic to mic. Move the mic or the instrument around to find that distance, and you will achieve a much better sounding recording.

Finally, there is a ton of hype around mic preamps.

Mic preamps sound different from one another, but the mic is the transducer, and it makes a far more significant difference. If the preamp is clean with decent headroom, it will be fine. I'd concentrate on the mics before going into the world of expensive preamps. And there are also some fairly inexpensive models that sound fantastic.

Great thread, Les. What are your thoughts on mic pres as they relate to different mic types?

It's funny, I was editing my post to include a little something on pres while you were posting!

I feel that assuming that you have an adequate mic preamp with decent headroom, way too much is being made of mic preamps. The mic is far more important in the signal chain. Put the money into the mic first. When you have good mics, then look at preamps.

If you want color, look to the transducer first. The mic.

Certainly, the preamp can make a difference, but I don't think it's as significant as the mic, the mic placement, and other factors, like the room the instrument is being recorded in.

Further, there are some inexpensive mic preamps on the market that are very impressive! For example, people forget that the Focusrite ISA series of preamps were designed by the master, Rupert Neve. You can buy one for $500, and it has a host of useful features, including impedance selection which is important for ribbon mics (ribbons want to see an impedance 5x the mic's impedance, so for a 300 ohm ribbon like the Royer, the mic wants 1500 ohm impedance). The UA mic preamp is also terrific, and the one in the Solo box costs under $800, as does the 710.

My son has gotten absolutely superb results with a Focusrite Platinum preamp that was very inexpensive (incidentally, he's the recording engineer on the current 30 Seconds to Mars record, he's no slouch!).

There are also some mic preamps that come on converter boxes that are very good, and some pretty poor quality ones as well. Caveat emptor on that stuff. Listen before you buy. The mic preamps on most modern consoles are fine.

I kind of cringe when I see people spending 3-4 grand on a single mic preamp for most home studios, though; in most cases the ambient noise is around 35-40db, where in a professional studio, it's far lower. You're simply not going to take advantage of what some of these boxes can do in most home environments.

What people often don't really understand is that a great mic preamp does two things that have nothing to do with "tone." One, they tend to have more headroom and faster slew rates, etc. Two, they sound a little more "focused." Using a great mic, with a great preamp, you will have a little crisper picture, with more definition around the edges of the recorded image. This is hard to describe, but bear with me: imagine a very fine paintbrush vs a spray can. The best mic preamps give you an image that has precisely defined edges, and this helps the sense of realism. It's a little more 3D.

The worst mic preamps give you an image that looks like it was done with a spray can, without much definition around the edges. So you have a fuzzy or unfocused image.

To me, this is where preamps differ the most. But in order to take advantage of this definition, you need a very quiet room! 20 db ambient noise, or so. This isn't achievable without soundproofing and special heating and air conditioning ductwork designed to be extremely quiet. The more ambient noise, you're not going to hear the definition as well anyway. So there are diminishing returns.

I feel that "grit" and "tube sound" and all that stuff should come in processors later in the signal chain, and not so much in the mic preamp, but that's just my philosophy.

There are also some 500 series mic preamps that are really great in the $500 range.

Other than switchable impedance to accommodate ribbons, I don't think the preamp needs to be matched to mic type as long as it has enough headroom and volume to go with the mic (and obviously, phantom power if that's needed, etc).

Lots of cool tips Les, the 57 on acoustic was one of those things that would freak people out whenever I would do it, but you can't deny the results. I'm not sure I agree 100% on your stance about colored mic pre's, but I feel you that you don't need to spend $3000 for one! There are lots of cool pre's that the recording world has forgotten about, and we are so lucky to be living in a time where we have so many options.

Lots of cool tips Les, the 57 on acoustic was one of those things that would freak people out whenever I would do it, but you can't deny the results. I'm not sure I agree 100% on your stance about colored mic pre's, but I feel you that you don't need to spend $3000 for one! There are lots of cool pre's that the recording world has forgotten about, and we are so lucky to be living in a time where we have so many options.

Thanks, Sergio. As to coloration on mic preamps, lots of other gear like EQ and compression adds more coloration, so I like the option of deciding on those kinds of choices later in the process, especially if I don't have a very, very clear idea of exactly what I want.

But I'm not against colored mic preamps; you just have to pay a lot for the good ones! I'm of the mindset that I'd rather start with good, and go from there, because you still have to add compression and EQ and whatever else to the processing so often.

But of course this is just my personal philosophy, and we're all different. Also, there isn't a mic preamp on the planet that isn't colored to some degree, so there's that. A lot of classic records were made on one console with its onboard mic preamps, not outboard ones.

In fact, in more recent times, the early Eminem hits were cut on a Mackie 8-Bus with the built in mic preamps. The board belongs to mega-hitmaker Jeff Bass, and is still the mainstay of his personal studio. I know Jeff, and have cut tracks at his place with this board. I think Jeff told me he made records that sold 30 or 40 million with this board. Not too shabby, eh? BTW, one of his guitars is a PRS Santana.

So yes, I do think an awful lot is made of stuff that may not matter ALL that much.

Your ordinary Shure SM57-style dynamic mic is actually a very fine recording mic, and an excellent transducer. Its strengths are that it's extremely robust and is able to capture the sound of a guitar speaker up close, and it can also do a nice job at a reasonable distance. The weakness of dynamic mics are that the method of transducing sound waves requires that the physical movement of a relatively heavy diaphragm. So it's more difficult to reproduce transients, and the attack portion of the waveform is a little more rolled off. It's also more accurate at the midrange than the low end or high end. People say mics like the 57 are midrange-heavy. Actually, they're high end and low end deficient with a relatively slow transient response. They are not horribly sensitive to proximity effect.

They're absolutely great for capturing certain elements of a guitar amp tone, and depending what you want to do with them, dynamic mics are well worth using. The key to getting a more natural sound with them is to use them close-in in combination with other mics.

OK, I'm guessing that SM57s and other dynamic mics would not be a good choice for micing a piano, then...

Thbbbbbt...
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